It’s true — thumb sucking beyond age 4 can cause bite problems for permanent teeth. But prolonged thumb sucking is just one of a number of possible contributing factors for a bad bite (malocclusion). A dentist must identify all the factors involved when a bad bite is present — their involvement is essential for a successful treatment outcome.

A fairly benign habit for infants and toddlers, thumb sucking is related to an “infantile swallowing pattern” young children use by thrusting their tongues forward between the upper and lower teeth when they swallow. Around age 4, though, they usually transition to an adult swallowing pattern in which the tongue rests on the roof of the mouth just behind the front teeth. Thumb sucking stops for most children around the same time.

Thumb sucking beyond this age, though, can put increased pressure on incoming permanent teeth pushing them forward. This could lead to an “open bite” in which the upper and lower teeth don’t meet when the jaws are closed. The tongue may also continue to thrust forward when swallowing to seal the resulting gap, which further reinforces the open bite.

Before treating the bite with braces, we must first address the thumb sucking and improper tongue placement when swallowing — if either isn’t corrected the teeth could gradually revert to their previous positions after the braces come off. Besides behavioral incentives, we can also employ a thin metal appliance called a “tongue crib” placed behind the upper and lower incisors. A tongue crib discourages thumb sucking and makes it more difficult for the tongue to rest within the open bite gap when swallowing, which helps retrain it to a more normal position.

An open bite can also occur if the jaws develop with too much vertical growth. Like thumb sucking and improper tongue placement, abnormal jaw growth could ultimately cause orthodontic treatment to fail. In this case, though, surgery may be necessary to correct the jaw structure.

With all these possible variables, our first step needs to be a thorough orthodontic exam that identifies all the cause factors for your child’s specific malocclusion. Knowing if and how thumb sucking may have contributed to the poor bite will help us design a treatment strategy that’s successful.